Apex domains cannot have CNAME records.
Question and response
Question
dig fbxo.proxad.net. NS
Answer
fbxo.proxad.net. 4 NS nsdb2.proxad.net.
fbxo.proxad.net. 4 NS nsdb1.proxad.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0